1. Field of the Invention
The blind spacer fastener of this invention offers a large potential in many areas wherein a given space is desired or required between structures being fastened. One such area is in sheet metal buildings where a foam spacer is used between the top sheet and the insulation blanket. Where the insulation blanket is resting on the roof support, often a purlin, the foam provides a spacer which is non-metallic between the top sheet and the support. Fasteners installed in this manner provide the possibility of attaching the top roof sheet without crushing the insulation blanket which would cause an insulation value loss of approximately 30%.
The fastener also has application when fastening honeycomb and the like to structural components so that the honeycomb structure will not collapse.
It is not necessary, however, that there be any material between the top and bottom sheets to which some other item is to be fastened; such fastener could, for example, be used to fasten something to a thin walled metal tubing.
In general the fastener concept of this invention may be utilized in those applications wherein it is important to keep the upper sheet(s) a desired or even a prescribed distance from the lower sheet(s). Other examples include foam filled panels, honeycomb panels, balsa wood panels with metal/plastic sheets, and stand-off where no material is between the upper and lower sheets. Other uses for this inventive concept will no doubt occur to those to whom the invention is made known.
2. Description of the Prior Art
A search of the prior art as represented by U.S. patents relating to this subject matter was conducted and the following U.S. Pat. Nos. were located: 3,078,002, 3,512,328, 3,055,255, 3,230,818, 3,667,340, 3,789,728, 3,797,358, 3,640,361.
Although it was the intent of the search to locate the art closest to that to which the invention is directed, no assertion is made that the patents listed are indeed representative of the best art.
U.S. Pat. No. 3,078,002 illustrates a blind fastener for honeycomb structure. While a number of embodiments are illustrated, in general they comprise a blind rivet pin or stem mounting a rivet head, a spacer sleeve and a lower cylindrical portion. Upon the pulling of the stem, the sleeve will cause the lower cylindrical member and the head to deform against the outer skins of the honeycomb, the sleeve serving as a spacer.
U.S. Pat. No. 3,512,328 illustrates a fastening device comprising a plastic screw 5, a blind rivet nut 4 and an additional screw 11. This reference illustrates the deformed portion 8 of blind rivet nut 4.
As indicated the search also turned up applicant's U.S. Pat. No. 3,230,818 which illustrates a blind rivet, the rivet sleeve of which is provided with longitudinal slots. U.S. Pat. No. 3,667,340 teaches a fastening device comprising a slotted sleeve 4 and a screw 27. The slotted sleeve permits lateral extension thereof.
Somewhat similar fastening means are set forth in the remaining patents but they do not appear to be closer than those discussed above.